Go Back   Home > Forums > > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Vendor's Bazaar Commercial Vendors large & small hawking their wares

New FIFO buffer for RPI/SBCs
New FIFO buffer for RPI/SBCs
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 5th August 2016, 06:27 PM   #11
cdsgames is offline cdsgames  Canada
diyAudio Member
 
Join Date: Jun 2015
I think I can see where you are going with this..

1. Yes of course its possible. Actually we are looking right now at the new generation Kali reclocker. Its not the FPGA that sends the i2s signals out (because of the high jitter inherent to fpga silicon) . The re-cloaking its done at output of FPGA using flipflops
2. How many bits of resolution ? Why 2 ics..many ADCs have 4 channels..

You are looking basically to make a digital active crossover device with microphone feedback .
  Reply With Quote
Old 6th August 2016, 12:02 AM   #12
steph_tsf is offline steph_tsf  Belgium
diyAudio Member
 
steph_tsf's Avatar
 
Join Date: Mar 2008
Quote:
Originally Posted by cdsgames View Post
You are looking basically to make a digital active crossover device with microphone feedback .
Better say microphone-based setup.

Typically :
1. Simply hook a TDA7801, and you'll get four 20 Watt channels, easy to handle as they are Class-AB. This is the beginner's stereo 2-way system.
2. Add a STA326 configured in stereo, and you become stereo 3-way, able to drive two 50 Watt woofers.
3. Add another STA326 configured in mono, and you can hook a 100 Watt subwoofer.
Attached is a .jpg explaining why during the microphone-based setup, it is recommended to feature four analog inputs (two identical stereo ADCs).
1. The bare speaker transfer function is equal to Mike (1 or 2) divided by DSP (1 or 2 or 3)
2. The DSP correction that's currently in use is equal to DSP (1 or 2 or 3) divided by Ref
3. The global transfer function is equal to Mike (1 or 2) divided by Ref
There are two distinct approaches regarding the software in charge of the setup :
1. Raspberry Pi as stand-alone. Requires a monitor, a pointing device, and a keyboard. Raspberry Pi to generate a pink noise, execute the DSP and compute the above transfer functions. Raspberry Pi to display realtime curves using HDMI.
2. Raspberry Pi as USB 4-channel audio out + bulk data in. Requires a PC. Raspberry Pi to generate a pink noise, execute the DSP, and return the 4 audio channels to the PC. PC to compute the above transfer functions. PC to display realtime curves. PC to communicate the required correction to the Raspberry Pi.
By relying on FIR filters, the setup can be automated.
1. You specify a global transfert function as target, in gain and in phase, having the format of a 1024-FFT. You can specify a Linkwitz-Riley 4th-order exhibiting the usual phase distorsion, or you can specify a Linkwitz-Riley 4th-order exhibiting no phase distorsion.
2. You measure the bare speaker transfer function (see above), also having the format of a 1024-FFT.
3. You compare the global transfer function with the bare speaker transfer function, in gain and in phase. The result of such comparison is the required correction function, in gain and in phase, also having the format of a 1024-FFT.
4. You do an inverse FFT of such data, delivering the impulse response of the required correction function, which actually is the 1024-tap FIR filter coefficients list of the DSP.
A few IIR Biquad filters can be manually added as channel equalizers each time a speaker driver is plagued by some severe high frequency resonance before extinction. This has the benefit of improving the stability/convergence of the automatic microphone-based setup, as this time the FIR filter doesn't need to battle against an impulse response that's corrupt by a big overshoot, and a long trailing edge.

IIR Biquad filters can be manually added in the context of a global equalizer like for reshaping the deep bass response, this is actually called a Linkwitz-Transform. Over there, a 32-bit resolution is mandatory, linear instead of floating point for the sake of the IIR Biquad filter stability and noise floor.

Best regards,
Steph
Attached Images
File Type: jpg DSP before DAC - 3-way speaker.jpg (73.5 KB, 1168 views)

Last edited by steph_tsf; 6th August 2016 at 12:05 AM.
  Reply With Quote
Old 7th August 2016, 07:52 AM   #13
nautibuoy is offline nautibuoy  United Kingdom
diyAudio Member
 
nautibuoy's Avatar
 
Join Date: Jan 2010
Location: Somerset, England
Looks like an interesting project cdsgames. Where can I find out more about the board, features, pricing, availability, etc.

Isolation would be a nice addition.
  Reply With Quote
Old 7th August 2016, 09:32 AM   #14
cdsgames is offline cdsgames  Canada
diyAudio Member
 
Join Date: Jun 2015
We looked at isolation , long and hard. However you have to isolate not only i2s , but also SPI , i2c and a bunch of other signals..the complexity and pricing of the board will increase significantly . In the end , we might release a second shield that will provide isolation for whomever needs it. As far as clocks , they are heavily filtered (LC , LDOs etc) so it does not matter than much.

For availability , we are currently talking to resellers and websites. Expect more news before the 25 August.
  Reply With Quote
Old 8th August 2016, 08:36 AM   #15
cdsgames is offline cdsgames  Canada
diyAudio Member
 
Join Date: Jun 2015
I am including a video of the Purepath so you can see the capabilities of soft. We are able to have 4 poles crossover filters , volume etc for files that are 24/192Khz
https://www.youtube.com/watch?v=fAbiMoIj53o

We send only HPF frequency's over 80Hz (chose from 60-150Hz) to main speakers and rest LPF to subwoofer.
Its hard to explain the sound improvement , but he unit sounds clean , effortless .

ETA to launch Aug 26. Price less than 50$
  Reply With Quote
Old 12th August 2016, 06:06 PM   #16
cph2000 is offline cph2000  Denmark
diyAudio Member
 
Join Date: Feb 2004
Location: San Diego
this looks like a nice little board at an attractive price
__________________
.
  Reply With Quote
Old 13th August 2016, 06:00 PM   #17
dudaindc is offline dudaindc  United States
diyAudio Member
 
dudaindc's Avatar
 
Join Date: Sep 2005
Location: Metro Washington DC
Quote:
Originally Posted by cdsgames View Post
...
ETA to launch Aug 26. Price less than 50$
__________________
"All measurements are wrong! Thus, measurement is the art of handling errors."
  Reply With Quote
Old 17th August 2016, 06:28 AM   #18
cdsgames is offline cdsgames  Canada
diyAudio Member
 
Join Date: Jun 2015
Attached is the LR flow. We are using biquad filters each filter is 2 pole and we cascade 2 filters so totally 4 pole in each channel.
Attached Images
File Type: png 5124flow.png (59.5 KB, 1707 views)
  Reply With Quote
Old 17th August 2016, 09:30 AM   #19
cdsgames is offline cdsgames  Canada
diyAudio Member
 
Join Date: Jun 2015
Default reclocker Kali giveaway

Hi all ,

we are looking to giveaway 3 (free) units for testing , please let us know of your interest. We are looking for reviewers with :

1.Fair amount of posts.
2. Audio on RPI experience .

that's it.
  Reply With Quote
Old 17th August 2016, 10:03 AM   #20
adelias is offline adelias  Greece
diyAudio Member
 
Join Date: Feb 2005
Location: No Pasaran
Will these boards be compatible with the Odroid C2?
  Reply With Quote

Reply


New FIFO buffer for RPI/SBCsHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
RPi 3 ifi ipower eis PC Based 10 12th October 2016 01:28 PM
RPI: Multichannel PCM over HDMI keylimesoda PC Based 0 28th January 2016 07:55 PM
RPi B+ and ES9018K2M DAC: can't get it to work! Feddo Digital Line Level 0 18th April 2015 01:41 PM
Volumio and Rpi DAC tjaekel PC Based 1 5th February 2014 02:34 PM
Using large buffer FIFO on SPDIF fed DAC wa2ise Digital Source 8 2nd February 2006 03:43 PM


New To Site? Need Help?

All times are GMT. The time now is 08:08 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki